Novel non-ionic polyurethane resins having polyether backbones in water-dilutable basecoats

ABSTRACT

This invention, therefore, relates to the field of polyurethane coatings for use in automobile basecoat/clearcoat systems. In particular, this invention relates to water-dispersible polyurethane resins having polyether sidechains which may be utilized in basecoat compositions as principal resins or grind resins. These polyurethane resins may be laterally stabilized or terminally stabilized. The terminally stabilized resins of this invention are preferably employed as principal resins in basecoat compositions.

This application is a division of application Ser. No. 077,353, filedJuly 24, 1987, now issued as U.S. Pat. No. 4,794,147.

BACKGROUND OF THE INVENTION

Multi-layer systems have been utilized to coat automobiles for a numberof years, but the early development of these systems necessarilyemployed organic solvents. As environmental regulations became morestringent, and the cost of organic solvents rose, organic-borne systemsbecame less desirable. The recent research emphasis in the area ofmulti-layer systems, especially basecoat systems has focused on thedevelopment of water-borne systems for multi-layer coatings.

The shift from organic solvents to water for dispersing and applyingresins in multi-layer systems solved many of the environmental and costproblems associated with the use of organic solvents. Water-bornesystems, however, have resulted in other problems.

One solution to these problems has been the development of anionicpolyurethane resins as described, for example, in Ser. No. 038,385 nowU.S. Pat. No. 4,179,168. These resins exhibit superior coatingcharacteristics in many basecoat/clearcoat multi-layer systems. However,in certain instances these resins may not be compatible with strong acidcatalyzed high-solids melamine-containing clearcoats, because of thetendency to exhibit wrinkling, and loss of DI (Distinctness of Image).

The polyurethane resins of the present invention, however, may be usedin the above-described melamine-containing systems without the negativecharacteristics exhibited by anionic resins. Thus, the combination ofnon-ionic polyurethane basecoats with strong acid catalysed clearcoatsallows for a lower composite Volatile Organic Content (VOC) than withanionic polyurethane basecoats.

The resins of the present invention have excellent water dispersibilityproperties, a surprising result considering the absence of salt-forminggroups. It is particularly surprising that these resins maintain theirwater dispersibility even when formulated as principle resins in basecoat compositions. It is also a surprising result, considering the waterdispersibility of these resins, that the resins of the present inventioncoalesce and hold firmly onto a vertical panel.

In a further aspect of the present invention the resins are formulatedinto grind resins for use in basecoats. Yet, aqueous dispersions ofnonionic polyurethanes are known in the literature and have been used toprepare films and coatings. Generally, polymer dispersions areunsuitable for use in milling pigments. It is quite surprising that theaqueous dispersions of the nonionic polyurethanes of the presentinvention are effective grind resins for a wide variety of pigments.

The present inventions, in part, directed to polyurethane coatings to beused in formulating basecoat compositions of multi-layer coatingsystems. These resins exhibit superior coating characteristics, forexample, good metallic effects such as very favorable arrangement,fixation, and flip effect of the metallic pigments in the paint film.When non-metallic pigments are used, the resins of the present inventionexhibit a high level of decorative effect.

This invention, therefore, relates to the field of polyurethane coatingsfor use in automobile basecoat/clearcoat systems. In particular, thisinvention relates to the discovery that incorporatingpolyether-containing compounds into the backbone of a polyurethane resinprovides basecoat coating compositions for a number of substrates.

These polyurethane coating compositions exhibit coating characteristicssuperior to those taught by the art and are especially useful asbasecoats for automobiles.

It is an object of this invention to provide polyether-containingpolyurethane resins that can be incorporated into basecoat formulationsas principle resins and/or grind resins. It is an additional object ofthis invention to provide water-dispersible resins which arewater-dispersible without incorporating salt-forming groups into theresins.

It is an additional object of this invention to providewater-dispersible polyurethane resins which exhibit superior coating andcosmetic characteristics.

It is a further object of this invention to provide aqueous polyurethanedispersions having favorable characteristics for formulating grindresins.

It is also an object of this invention to provide a method of producingthe resins and basecoat compositions described herein.

It is a further object of this invention to provide a method for coatinga metallic or plastic substrate utilizing the resins and basecoatformulations of the present invention.

These and other objects of the present invention are furthered byincorporating polyether-containing polyurethane resins into basecoatformulations.

SUMMARY OF THE INVENTION

Two types of polyether-containing polyurethane resins are described inthe present invention. We have termed these two types of resinslaterally stabilized and terminally stabilized.

Specifically, this invention relates to a laterally stabilizedpolyurethane coating composition comprised of:

1. at least one organic compound having at least two reactive hydrogenatoms;

2. a nonionic stabilizer prepared by the reaction of:

(i) a monofunctional polyether with a first polyisocyanate-containingcompound to produce a partially capped isocyanate intermediate; and

(ii) a compound having at least one active amine hydrogen and at leasttwo active hydroxyl groups; and

3. at least one second polyisocyanate-containing compound.

The organic compound preferably comprises a polyester polyol, a lowmolecular weight diol/triol or mixtures, thereof. Optionally, a cappingagent is employed to cap any remaining free isocyanate moieties.

In addition, this invention also relates to terminally stabilizedpolyurethane compositions comprised of:

(1) at least one organic compound having at least two reactive hydrogenatoms;

(2) ,a monofunctional polyether; and

(3) a polyisocyanate.

The organic compound of the terminally stabilized polyurethanecompositions preferably comprises a polyester polyol, a low molecularweight diol and/or triol, or mixtures thereof. Optionally, a separatetrifunctional hydroxyl containing monomer is employed for use in thepolyurethane resins of the present invention. Optionally, a cappingagent is employed to cap any remaining free isocyanate moieties

In the laterally stabilized polyurethane resins, the incorporation ofthe polyether groups functions to chain extend the polyurethane resin.In contrast, the incorporation of the polyether groups in the terminallystabilized polyurethane resin functions to terminate the resin. The twotypes of polyurethane resins described above can be formulated as awater-dispersed basecoat composition which contains in addition toeither of the above-described resins a grind resin, a cross-linkingagent, thixotropic or rheology control agents, thickeners, pigments,aluminum and/or mica particles, basifying agents, water, fillers,surfactants, stabilizers, plasticizers, wetting agents, dispersingagents, adhesion promotors, defoamers, catalysts, and additionalpolymers.

In preferred embodiments of basecoat compositions of the presentinvention, the terminally stabilized polyurethane resin is utilized asthe principle resin and the laterally or terminally stabilizedpolyurethane resins is utilized as the grind resin.

After formulation, the basecoat composition can be sprayed or depositedonto an automobile body, preferably, in one or two coats. Generally, twoeven coats of basecoat are applied with a several minute flash betweencoats. After deposition of the basecoat, before application of a highsolids content clear coat, it is generally preferred to flash about 90%of the water from the basecoat for optimum appearance and to eliminatewater boil of the clearcoat.

In both the linear and branched chain polyurethane resin, a polyesterpolyol resin is preferably a major component.

The polyester polyol resins described hereinabove are themselves usefulon virtually any elastomeric substrate, but they are particularly usefulwhen formulated into polyurethane coatings and used in basecoatformulations for deposition onto metal or plastic substrates, especiallyautomobile bodies.

The polyester component may be any type, i.e., branched or unbranched,and is formed from the reaction of at least one dicarboxylic acidcomponent and at least one alcohol component wherein the alcohol has atleast two hydroxyl

Virtually any carboxylic acid-containing compound having two or morecarboxylic acid moieties or equivalents that are useful in synthesizingpolyester compounds are useful in the present invention.

The carboxylic acid component may, of course, be comprised ofshort-chain dicarboxylic acid compounds, long chain dicarboxylic acidcompounds, or mixtures thereof. By short chain dicarboxylic acids wemean compounds having at least two carboxylic acid moieties and fewerthan 18 carbon atoms in the chain. These dicarboxylic acids may bealkyl, alkylene, aralkyl, aralkylene, and arylene, among others. In thepolyester resins of the present invention the carboxylic acid containingcompound may be polyfunctional with 2 or more carboxy groups. Apreferred carboxylic-containing compound for use in branched polyesterresins is trimellitic anhydride. Short-chain alkyl or aryl dicarboxylicacid compounds for example azeleic acid, adipic acid, or an equivalentaliphatic or aromatic acid are preferred. A preferred aromaticdicarboxylic acid is isophthalic acid.

The carboxylic acid component may also be comprised of a long-chaindicarboxylic acid component. This long-chain dicarboxylic acidcontaining compound may be an alkyl, alkylene, aralkyl, aralkylene orsimilar compound, but it must be stressed that virtually any long-chaindicarboxylic acid containing compound may be used. An especiallypreferred long-chain carboxylic acid-contining compound is C36dicarboxylic acid known as dimer acid. A discussion of dimer acid can befound in U.S. Ser. No. 038,385 which is incorporated by referenceherein. As in the case of the short-chain dicarboxylic acid-containingcompounds, linear dicarboxylic acid-containing compounds may bepreferably used in linear polyurethane resins, and linear or brancheddicarboxylic acid containing compounds may be preferably used inbranched chain polyurethane resins.

In addition to the carboxylic acid containing compound, the polyesterresin is also comprised of one or more low molecular weight diols ortriols. We have termed any compound having more than one alcohol apolyol. Polyols may be diols (di-alcohol containing), triols(tri-alcohol containing) or higher alcohol-functional compounds in thecase of the branched- chain polyurethanes, the amount and type oftriol-containing compounds may be varied to increase the branchingeffect. A preferred trialcohol-containing compound for use in thebranched chain polyesters is trimethylol propane.

The polyester resin or mixture of polyester resins utilized tosynthesize the polyurethane resins preferably are hydroxyl terminated.This is effected by synthesizing the polyester using an excess of a diolor triol-containing compound. The relative weights of the carboxylicacid component and alcohol-containing compound depend upon the desiredchain length of the polyester compound employed. The result of thissynthesis is a polyester having two or more free hydroxyl groups(polyesterdiol or polyol).

The composition of the carboxylic acid component and polyol componentemployed to synthesize the preferred polyester resins is such as toprovide an excess of the polyol over and above the total number ofequivalents of acid present in the mixture. In other words, thereactants should be selected, and the stoichiometric proportions of therespective acid and polyol components should be adjusted to givehydroxy-terminated, polyester molecules each theoretically having ahydroxyl functionality of 2 or more.

Monocarboxylic acid and monoalcohols may also be used in the polyestersynthesis, but these are generally utilized for the purpose of chainterminating a polyester resin. As a general rule, where used, themonocarboxylic acids and/or monoalcohols comprise a very smallpercentage by weight of the final polyester resin.

As a general rule the polyester diol component comprises between about20% and 80% by weight of the final polyurethane resin. Preferably thepolyester diol comprises between about 50 and 70% by weight of thepolyurethane resin and most preferably the polyester diol comprisesbetween about 5 and 65% by weight.

While it is recognized that almost any size chain length of polyesterpolyol can be utilized, it is preferable to use a polyester diol withinthe molecular weight range of between 500 and 5000. It is preferablethat the molecular weight range of the polyester diol component bebetween 1,000 and 3,500.

In addition to the polyester diol, the polyurethane resins of thepresent invention are also comprised of additional organic compoundshaving at least two reactive hydrogen atoms. This component ispreferably a low molecular weight diol or triol compound but may containalcohol groups, thiols and/or amines or mixtures of thesefunctionalities. The same alcohol-containing compounds utilized tosynthesize the polyester-containing compound may be utilized as aseparate component here. Thus, any di or tri-alcohol containing compoundmay be used, for example neopentyl glycol and 1,6 hexanediol. Highmolecular weight diols and triols are not preferred, however, where thehydrophobicity of their molecular chains impacts on thewater-dispersibility of the final polyurethane resins. The purpose ofthis alcohol containing component is to provide chain extension and/orbranching through the isocyanate containing compounds. Thus, dependingupon the desired amount of chain extension and/or branching desired inthe final polyurethane resin, varying weight percentages and types ofdiols and/or triols may be utilized. Where linear polyurethane resinsare desired the ratio of diol-containing compounds to triol-containingcompounds may be higher than when or branched chain polyurethanecompounds are desired.

The amount of low molecular weight diol and/or triols utilized in thepolyurethane resins of the present invention may vary between 0 and 20percent by weight of the polyurethane resin. Preferably this lowmolecular weight alcohol component comprises between about 0 and 10percent of the polyurethane resin and most preferably comprises betweenabout 1 and 6% by weight of the polyurethane resin.

The polyurethane resins of the present invention further comprise apolyisocyanate, preferably a diisocyanate. Generally, the diisocyanatecomprises between about 5 and 40% by weight of the final polyurethaneresin. Preferably, the diisocyanate comprises between about 10 and 30percent by weight of the final resin and most preferably comprisesbetween about 10 and 20 percent by weight of the polyurethane resin.

A polyether-containing compound provides the polyurethane resin with thepreferred water dispersibility characteristics. Thesewater-dispersibility characteristics are inured to the polyurethaneresins of the present invention without the need to incorporatesalt-forming groups within the resin. The absence of salt-forming groupsenables the polyurethane resins to be incorporated into basecoatcompositions which may be utilized in combination with strong acidcatalysed high solids melamine-containing clearcoats. This results in alower composite VOC coating which does not exhibit the same wrinkling,loss of DI (distinctive image) "browning" effects shown by thecation-containing polyurethane resins.

Two different approaches for incorporating polyether segments into thepolyurethane resins are available depending upon the type ofpolyurethane resin desired. The approach to synthesizing a laterallystabilized polyurethane utilizes a polyether diol prepared from thereaction of a monofunctional polyether with a diisocyanate to form apolyether half-capped diisocyanate. This half-capped diisocyanate isthen reacted with a compound having one active amine hydrogen and atleast two active hydroxyl groups to form a non-ionic stabilizer(polyether diol) having a polyether chain, a urea moiety, a urethanemoiety, and two free hydroxyl groups.

Once synthesized, the non-ionic stabilizer is then added to a reactionmixture comprised of at least one organic compound having two or morereactive hydrogen functionalities, and an excess of apolyisocyanate-containing compound (in addition to that which isincorporated into the nonionic stabilizer). Preferably a polyesterpolyol is also added to form the polyurethane. Optionally, a cappingagent, for example, trimethylol propane or diethanolamine may be used tocap any remaining free isocyanate groups. The resulting laterallystabilized polyurethane resin may be formulated in a basecoatcomposition and is preferably utilized as a grind resin. The laterallystabilized polyurethane resin may also be formulated as a principalresin, but for purposes of the present invention, the terminallystabilized polyurethane resin is preferably utilized as the principalresin, and can also be used as a grind resin.

The polyether component which instills water dispersible characteristicsto the laterally stabilized and the terminally stabilized branched-chainpolyurethane resin is a polyether having one functional group, forexample methoxypolyethylene glycol, among others. The polyethercomponent is generally produced by utilizing a monoalcohol initiatedpolymerization of ethylene oxide, propylene oxide or mixtures thereof.The functional group on the polyether compound may be any group reactivewith isocyanates to form a stable product. Thus, the polyether compoundmay contain a free hydroxyl, thiol, or amine, but hydroxylfunctionalities are preferred to minimize the possibility of saltformation.

In the laterally stabilized polyurethane resin, the monofunctionalpolyether compound is, as previously described, reacted with apoly-isocyanate-containing compound to form a half-capped isocyanate.This half-capped isocyanate is then reacted with a compound having anamino active hydrogen and at least two free hydroxyl groups (orequivalent functionalities). This resulting product, termed the nonionicstabilizer, is then incorporated into the polyurethane resin by reactionwith the other components. In contrast, in the terminally stabilizedpolyurethane resin, the polyether functionalitiy is incorporated intothe resin as the monofunctional polyether.

The monofunctional polyether compound is reacted with a mixturecomprised of at least one polyester polyol, a polyisocyanate, and inaddition, optionally a short chain low molecular weight diol or higherfunctional polyol, or mixtures of diols and polyols. Optionally, acapping agent, for example, trimethylolpropane or diethanol amine may beused.

For the terminally stabilized polyurethane, the polyester diolpreferably comprises between 20 and 80% by weight of the finalpolyurethane resin and generally has a molecular weight between about500 and 5,000, preferably between 1,000 and 3,500. Preferably, thepolyester polyol component comprises between about 50 and 70% and mostpreferably between about 55 and 65% by weight of the polyurethane resin.

The terminally stabilized polyurethane resin may be comprised of thesame weight percentages of the low molecular weight diol/triol componentas the laterally stabilized polyurethane resin. Where thesealcohol-containing compounds are mixed, it is preferred that the ratioof triol/diol be higher for the terminally stabilized polyurethaneresins than in the case of laterally stabilized polyurethane resins.

The same weight percentages of polyiisocyanate used in the laterallystabilized polyurethane are used in the terminally stabilizedpolyurethane. Preferably, the polyisocyanate is a diisocyanatecomprising between about 10 and 30% and most preferably between about 10and 20% by weight of the polyurethane.

In both the laterally stabilized and terminally stabilized polyurethaneresins, the polyether component may be multi-functional (the functionalgroups being hydroxyls, thiols, or amines with hydroxyl groupspreferred), and preferably is a mono or di- functional polyether withmonofunctional polyethers being particularly preferred. In general,water soluble polyether-containing compounds are useful in embodimentsof the present invention. Polyethers formed from monoalcohol initiatedpolymerization of ethylene oxide, propylene oxide and mixtures, thereofare preferred. Of course, very minor amounts of butylene oxide ethersand other longer chain ethers may be incorporated into the polyetherchain without adversely affecting the water dispersibility of theresins. Most preferably, ethylene oxide polymers comprise 100% of thepolyether component. In general, the polyether containing componentcomprises between about 2 and 40% by weight of the polyurethane,preferably betwen about 8 and 30% by weight, and most preferably betweenabout 10 and 25% by weight of the final polyurethane resin.

The molecular weight of the polyether-containing compounds in generalranges from about 500 to about 7000, preferably ranges from about 1000to 4000, and most preferably ranges from about 1200 to 3000.

The polyurethanes of the present invention are advantageously storagestable and are, of course, water dispersible. The water dispersibilityof the resins is controlled by the amount of polyether charactercontained in the final resin particles and the hydrophobicity of thenon-polyether components.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a water-soluble nonionic polyurethaneresin produced by incorporating a polyether-containing compound into theresin. The invention of the present application relates to lateralstabilization polyurethane resins and terminal stabilizationpolyurethane resins having polyether side chains. The laterallystabilized polyurethane resin is preferably comprised of the reactionproduct of :

1) a polyester polyol which is further comprised of the reaction productof a carboxylic acid-containing product having at least two carboxylicacid functionalities and a compound having at least two alcoholfunctionalities.

2) at least one low molecular weight compound having at least 2 alcoholfunctionalities.

3) at least one polyisocyanate-containing compound;

4) a nonionic stabilizer prepared by the reaction of a monofunctionalether with a polyisocyanate containing compound to produce a partiallycapped polyisocyanate followed by reaction with a compound containing atleast one active amine hydrogen and at least two active hydroxyl groupsand;

5) optionally, a capping agent is used to cap any remaining isocyanategroups that have not yet reacted.

The terminal stabilization polyurethane resin is preferably comprised ofthe reaction product of:

1) a polyester polyol,

2) at least one low molecular weight diol or triol;

3) a polyisocyanate;

4) a trihydroxy-containing monomer;

5) a monofunctional hydroxy-containing polyether; and

6) optionally, a capping agent.

The polyester component is not particularly critical to the presentinvention, but it is necessary that the polyester component becompatible with the desired water-dispersible characteristics of theresins described herein.

Thus, the carboxylic acid component of the polyester may be comprised oflong-chain dicarboxylic acids, short-chain dicarboxylic acids, mixturesthereof or carboxylic acid equivalents such as anhydrides, lactones, andpolycarbonates, among others. Long-chain monocarboxylic acids may alsobe used, but these are generally employed to chain terminate thepolyester resin.

The shorter chain carboxylic acid component, if used, may be comprisedof a mono-, di- or higher functionality carboxylic acids or a mixture ofthese carboxylic acids having carbon chains of 18 or fewer carbon units.Monocarboxylic acids function to terminate a polyester chain and arechosen for that purpose. It is preferable that the short chaincarboxylic acid component be a dicarboxylic acid. Such preferreddicarboxylic acid compounds include, for example, adipic, azeleic, andother aliphatic dicarboxylic acids, however, any dicarboxylicacid-containing compound compatible with the goal of maximizingwater-dispersibility may be utilized. Aromatic dicarboxylic acids mayalso be employed. An especially preferred aromatic dicarboxylic acid isisophthalic acid. Alkylene and aralkylene carboxylic acids may also beused. Where branched-chains in the polyester are desired, a carboxylicacid containing three or more carboxylic acid groups, for example citricacid, may be used. A preferred carboxylic acid-containing compound ofthis type is trimellitic anhydride.

The polyester resins are synthesized from the above-described carboxylicacid component and an excess of a polyol component. An excess of polyolis used so that the polyester resin preferably contains terminalhydroxyl groups. The polyol compounds preferably have an averagehydroxy-functionality of at least 2.

The polyester resin in most cases is comprised of one or more polyols,preferably a diol. Up to about 25 percent by weight of the polyolcomponent may be a polyol having three or more hydroxy groups permolecule. Where polyols having three or more hydroxy groups are chosen,the result is a branched polyester. As a general rule, the laterallystabilized polyurethane resin is comprised of a polyester having no morethan about 15 percent by weight of the alcohol-containing component of apolyol having three or more alcohol functionalities. The terminalstabilization polyurethane may be comprised of the same relativepercentages of tri-alcohol-containing component as that of the polyesterutilized in the lateral stabilization polyurethane, or alternatively,may be comprised of a tri-alcohol-containing polyol of up to 25 percentby weight of the polyol component.

While it is not always desirable to have a triol or highermulti-functional alcohol present because of the tendency to form abranched chain polyester, some branching may be desirable, especially inthe case where the polyester is to be incorporated into a branchedpolyurethane. There may also be present a small amount of monoalcohol inthe polyol component, particularly if larger proportions of higherfunctional alcohols are used. These monoalcohols serve as chainterminators.

The diols which are usually employed in making the polyester resinsinclude alkylene glycols, such as ethylene glycol, propylene glycol,butylene glycol, and neopentyl glycol, 1,6 hexanediol and other glycolssuch as hydrogenated bisphenol A, cyclohexane dimethanol, caprolactonediol (i.e., the reaction product of caprolactone and ethylene glycol),hydroxyalkylated bisphenols, and the like. However, other diols ofvarious types and, as indicated, polyols of higher functionality mayalso be utilized. Such higher functional alcohols can include, forexample, trimethylolpropane, trimethylolethane, pentaerythritol, and thelike, as well as higher molecular weight polyols.

The low molecular weight diols which are preferred in the presentinvention are well known in the art. They have hydroxy values of 200 orabove, usually within the range of about 1500 to 2000. Such materialsinclude aliphatic diols, particularly alkylene polyols containing from 2to 18 carbon atoms. Examples include ethylene glycol, 1,4-butanediol,cycloaliphatic diols such as 1,2 cyclohexanediol and cyclohexanedimethanol. An especially preferred diol is 1,6 hexanediol.

To produce the laterally stabilized polyurethane resins which are usefulin basecoat compositions of the present invention, the above-describedpolyester polyol is reacted with a mixture of a polyisocyanate,optionally a low molecular weight diol and/or triol, and a nonionicstabilizer comprised of, in part, a polyether containing compound. Twogeneral synthetic approaches are utilized to synthesize the polyurethaneresins of the present invention. The first approach is to react allproducts in one pot using an excess of hydroxy equivalents whensynthesizing the polyurethane resin (capping occurs simultaneously withthe synthesis of the polyurethane resin). Alternatively, an excess ofisocyanate is utilized to form an intermediate polyurethane which isthen capped with a capping agent such as trimethylol propane,diethanolamine, diols, or mixtures of diols, triols, etc.

The polyester polyol, polyisocyanate, low molecular weight diols and/ortriols, and nonionic stabilizer may be reacted in the same pot, or maybe reacted sequentially, depending upon the desired results. Sequentialreaction produces resins which are more ordered in structure. Both thepolyester and triol containing compounds may serve as chain extenders tobuild up the polyurethane backbone through reaction of hydroxyl groupswith isocyanate groups. Additional chain extenders having at least twoactive hydroxyl groups (diols, thiols, amines, or mixtures of thesefunctional groups) may be added to increase the chain length or tochange the chemical characteristics of the polyurethane resin. An excessof polyisocyanate is preferably used so that an intermediatepolyurethane resin can be produced having free isocyanate groups at theends. The free isocyanate groups may then be preferably capped withtrimethylol propane or diethanolamine. The low molecular weightdiols/triols/higher functional alcohols which are utilized as a separatecomponent in synthesizing the polyurethane resins of the presentinvention include alkylene glycols, for example ethylene glycol,propylene glycol, butylene glycol, and neopentyl glycol, among others.Additional alkylene glycols include cyclohexane dimethylol andcaprolactone diol. Exemplary higher functional alcohols includetrimethylol propane, trimethylolethane and pentaerythritol.

The organic polyisocyanate which is reacted with the polyester polyoland low molecular weight diol and/or triol material as described isessentially any polyisocyanate, i.e., any compound containing at leasttwo isocyanate groups, and is preferably a diisocyanate, e.g.,hydrocarbon diisocyanates or substituted hydrocarbon diisocyanates. Manysuch organic diisocyanates are known in the art, including p-phenylenediisocyanate, biphenyl 4,4'diisocyanate, toluene diisocyanate,3,3'-dimethyl-4,4 biphenylene diisocyanate, 1,4-tetramethylenediisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexane-1,6diisocyanate, methylene bis (phenyl isocyanate), 1,5 naphthalenediisocyanate, bis (isocyanatoethyl fumarate), isophorone diisocyanate(IPDI) and methylene-bis- (4 cyclohexylisocyanate). There can also beemployed isocyanate-terminated adducts of diols, such as ethyleneglycol, or 1,4-butylene glycol, etc. These are formed by reacting morethan one mol. of a diisocyanate, such as those mentioned, with one mol.of a diol to form a longer chain diisocyanate. Alternatively, the diolcan be added along with the diisocyanate.

While diisocyanates are preferred, other multifunctional isocyanates maybe utilized. Examples are 1,2,4-benzene triisocyanate and polymethylenepolyphenyl isocyanate.

It is preferred to employ an aliphatic diisocyanate, since it has beenfound that these provide better color stability in the finished coating.Examples include 1,6-hexamethylene diisocyanate, 1,4-butylenediisocyanate, methylene bis (4-cyclohexyl isocyanate) and isophoronediisocyanate 2,4 toluene diisocyanates is also preferred. Mixtures ofdiisocyanates can also be employed.

The proportions of the diisocyanate, polyester, diol and/or triolcomponent and nonionic stabilizer or monofunctional polyether are chosenso as to provide an isocyanate terminated intermediate polyurethaneresin. This can be accomplished by utilizing a stoichiometric excess ofpolyisocyanate, i.e., more than one isocyanate group per nucleophilicmoiety (reactive with isocyanate) in the other components. The freeisocyanates that remain after reaction may then be capped with a cappingagent, for example, trimethylol propane.

Longer-chain polyurethane resins may be obtained by chain extending thepolyurethane chain with diol and/or triol-containing compounds. Inaddition, although it is not preferred, additional chain extendingcompounds having at least two active hydrogen groups for example diols,dithiols, diamines, or compounds having a mixture of hydroxyl, thiol,and amine groups, for example, alkanolamines, aminoalkyl mercaptans, andhydroxyalkyl mercaptans, among others may be used. For purposes of thisaspect of the invention both primary and secondary amine groups areconsidered as having one active hydrogen. Alkanolamines, for example,ethanolamine or diethanolamine, may be used as chain extenders, and mostpreferably, a diol is used.

Examples of preferred diols which are used as polyurethane chainextenders include 1,6 hexane diol, cyclohexanedimethylol, and1,4-butanediol. A particularly preferred diol is neopentylglycol.Polyhydroxy compounds containing at least three hydroxyl groups may alsobe used as chain extenders; the use of these compounds produces branchedpolyurethane resins. For purposes of the present invention, if it ispreferred to minimize the amount of branching in the polyurethane resinthese polyhydroxy compounds should be limited to a very minor componentof the polyurethane producing mixture. These higher functionalpolyhydroxy compounds include, for example, trimethylolpropane,trimethylolethane, pentaerythritol, among other compounds.

The polyurethane resin may be chain extended in any monomer using thesediol and triol containing compounds or alternative compounds having atleast two active hydrogen groups. Thus, these compounds may be added tothe mixture of polyisocyanate, polyester, and polyether containingcompound, (nonionic stabilizer or monofunctional polyether compound), oralternatively, may react at an intermediate stage, to link two freeisocyanate groups that are present at the terminal ends of anintermediate polyurethane resin.

The polyether containing compounds, as described hereinabove, arepreferably mono or di-functional polyethers with mono-functionalpolyethers being particularly preferred. The monofunctional polyethersare preferably formed from monoalcohol initiated polymerization ofethylene oxide, propylene oxide, and mixtures thereof. A polyethercompound comprised of 100% ethylene oxide units is especially preferred.In its most preferred embodiment, the monofunctional polyether comprisesbetween 10 and 25% by weight of the final polyurethane resin and has amolecular weight of between 1200 and 3000.

It is generally preferred that an intermediate polyurethane resinproduced by reacting the polyester resin and the mixture ofpolyisocyanate, diol/triol mixture and polyether-containing compound beterminated with free isocyanate groups. To accomplish this, an excess ofthe polyisocyanate component is used. Thus, the diols/triols, polyethercomponent and polyester diol will all react with isocyanate moieties toproduce polyurethane resins having at least some free isocyanate groups.Of course, the molar ratio of the other components will be adjustedaccording to the desired characteristics of the intermediate and finalpolyurethane resins.

In one especially desirable embodiment of the invention, amulti-functional alcohol, for example, trimethylol propane is used toterminate the reaction (cap the free isocyanate groups) at the desiredstage (determined by the viscosity and isocyanate groups present),thereby also contributing residual hydroxyl groups. Particularlydesirable for such purposes are aminoalcohols, such as ethanolamine,diethanolamine and the like, since the amino groups preferentially reactwith the isocyanate groups present. These capping agents are especiallypreferred for use in the grind resin aspect of the present invention.Multi-functional alcohols, such as ethylene glycol, trimethylolpropaneand hydroxyl-terminated polyesters, can also be employed in this manner.

While the ratios of the components of the polyester, themulti-functional isocyanate, the diol/triol mixture, the polyethercontaining compounds, and the capping agent can be varied, it will benoted by those skilled in the art that the amounts should be chosen soas to avoid gellation and to produce an ungelled, urethane reactionproduct containing hydroxyl groups. The hydroxyl value of the finalpolyurethane reaction product should be at least 5 and preferably about20 to about 200.

The amount of polyisocyanate used in the mixture is preferably betweenabout 10% and 30% by weight of the reactants in the mixture, and mostpreferably between about 10 and 20%, but will vary depending upon thepolyester used and the desired molecular weight of the finalpolyurethane resin. The amount of polyisocyanate will also varydepending upon whether it is desired to have the intermediatepolyurethane terminated with free isocyanate groups or with hydroxylgroups. Thus, where it is preferred to terminate the intermediatepolyurethane resin with free isocyanates for capping withtrimethylopropane or diethanolamine, an excess of polyisocyanate may beused. Where the intermediate polyurethane resin is to be terminated byhydroxyl groups, a stoichiometric deficiency of polyisocyanate may beused.

The polyurethane resins of the present invention are formulated, alongwith other components, into water dispersible basecoat compositionswhich are sprayed or electrostatically deposited onto metal or plasticsubstrates, for example, automobile bodies. In general, a polyurethaneresin, formulated as described herein, is mixed with an aminoplastresin, a polyisocyanate or other cross-linking agent, a grind resin,water, a portion of an organic solvent, pigments and a rheology controlagent. Other agents may be included, for example, various fillers,surfactants, plasticizers, stabilizers, wetting agents, dispersingagents, defoamers, adhesion promoters and catalysts in minor amounts. Inone embodiment a branched-chain polyester component may also be added tothe basecoat composition.

As indicated, an aqueous dispersion of the polyurethane resin isutilized as the principal or major vehicle resin. In general, theprincipal or major vehicle resin comprises between about 0 and 90% byweight of the total solids present in the basecoat composition. Anacceptable polyurethane resin for use as the principal resin is a resinproduced from a polyester synthesized from dimer fatty acid, isophthalicacid, and 1,6 hexanediol. The resulting polyester is then reacted with adiisocyanate of isophorone, a triol and a polyether monoalcohol and adiol, for example, neopentyl glycol. The resulting polyurethaneintermediate having free isocyanate groups is then reacted withtrimethylolpropane to cap these groups.

The polyurethane reaction product as described above may be mixed withan aminoplast resin or a polyisocyanate cross-linking agent. Aminoplastresins are aldehyde condensation products of melamine, urea, and similarcompounds. Products obtained from the reaction of formaldehyde withmelamine, urea or benzoguanamine are most common and are preferredherein. However, condensation products of other amines and amides canalso be employed, for example, aldehyde condensates of triazines,diazines, triazoles, guanidines, guanamines and alkyl and arylsubstituted derivatives of such compounds, including alkyl and arylsubstituted ureas and alkyl and aryl substituted melamines. Someexamples of such compounds are N,N'-dimethylurea, benzourea,dicyandiamide, formoguanamine acetoguanamine, ammeline,2-chloro-4,6-diamino-1,3,5-triazine,6-methyl-2,4-diamino,1,3,5-triazine, 3-5-diamino-triazole,triaminopyrimidine, 2-mercapto-4,6-diaminopyrmidine, 2,4,6-triethyltriamino-1,3,5-triazine, and the like.

While the aldehyde employed is most often formaldehyde, other similarcondensation products can be made from other aldehydes, for example,acetaldehyde, crotonaldehyde acrolein, benzaldehyde, furfural, andothers.

The amine-aldehyde condensation products may contain methylol or similaralkylol groups, and in most instances at least a portion of thesealkylol groups are etherified by a reaction with an alcohol to provideorganic solvent-soluble resins. Any monohydric alcohol can be employedfor this purpose, including such alcohols as methanol, ethanol,propanol, butanol, pentanol, hexanol, heptanol, as well as benzylalcohol and aromatic alcohols, cyclic alcohols, for example,cyclohexanol, monoethers or glycols such as Cellosolves and Carbitols™(Union Carbide), and halogen-substituted or other substituted alcohols,such as 3-chloropropanol. The preferred amine-aldehyde resins areetherified with methanol or butanol.

Alternatively, isocyanate-containing compounds such as those previouslydescribed may be used as cross-linking agents. Generally, whenpolyisocyanates are used they comprise between about 1 and 50% of thebasecoat composition. Preferably, a fully blocked polyisocyanate is usedas a crosslinking agent.

In the preparation of the blocked organic polyisocyanate any suitableorganic polyisocyanate may be used. Examples include the aliphaticcompounds such as trimethylene, tetramethylene, hexamethylene,1,2-propylene, 1,2-butylene. 2,3-butylene, 1,3-butylene, ethylidine andbutylidene diisocyanates; the cycloalkylene compounds such as1,3-cyclopentane, 1,4-cyclohexane, and 1,2-cyclohexane diisocyantes; thearomatic compounds such as an phenylene, p-phenylene,4,4'-dipheny-1,1,5-naphthalene and 1,4-naphthalene diisocyanates, thealiphatic-aromatic compounds such as 4,4' diphenylene methane, 2,4 or2,6-tolylene, or mixtures thereof, 4,4' toluidine, and 1,4-xylylenediisocyanates: the nuclear substituted aromatic compounds such asdianisidine diisocyanate,4,4'-diphenylether diisocyanate andchlorodiphenylene diisocyanate, the triisocyanates such as triphenylmethane-4,4', 4"-triisocyanate, 1,3,5-trisocyanate benzene and2,4,6-triisocyanate toluene; and the tetraisocyanates such as4,4'-diphenyl-dimethyl methane 2,2', 5,5'-tetraisocyanate; thepolymerized polyisocyanates such as tolylene diisocyanate dimers andtrimers and the like.

Any suitable aliphatic, cycloaliphatic aromatic alkyl monoalcohol andphenolic compound may be used as blocking agent in accordance with thepresent invention, such as for example, lower aliphatic alcohols, suchas methyl, ethyl, chloroethyl, propyl, butyl, cyclohexyl, heptyl, octyl,nonyl 3,3,5-trimethyhexanol, decyl and lauryl alcohols, and the like,the aromaticalkyl alcohols, such as phenylcarbinol,methylphenylcarbinol, ethyl glycol monoethyl ether, ethyl glycolmonobutyl ether and the like; the phenolic compounds such as phenolitself, substituted phenols in which the substituents do not adverselyaffect the coating operations. Examples include cresol, xylenol,nitrophesol, chlorophenol, ethylphenol, 1-butyl phenol and2,5-di-t-butyl- 4-hydroxy toluene. Minor amounts of even highermolecular weight relatively nonvolatile monoalcohols may also be used.

Additional blocking agents include tertiary hydroxyl amines such asdiethylethanolamine and oximes such as methylethyl ketone oxime, acetoneoxime and cyclohexanone oxime. Use of oximes and phenols is particularlyuseful because specific polyisocyanates blocked with these agents uncapat relatively low temperatures without the need for externally addedurethane forming catalysts such as those described below.

The organic polyisocyanate-blocking agent adduct is formed by reacting asufficient quantity of blocking agent with the organic polyisocyanate toinsure that no free isocyanate groups are present.

A grind resin may also be used in the basecoat compositions of thepresent invention. The grind resin may be comprised of a number of watersoluble polyurethane resins, which may be different in chemicalcharacter to the principal or major vehicle resin, e.g., in a particularbasecoat formulation a terminally stabilized polyurethane compound maybe used as the principal resin and a laterally stabilized polyurethaneresin be used as the grind resin. Both laterally stabilized andterminally stabilized nonionic polyurethane resins of this invention maybe used as grind resins to formulate paint. The grind resin may rangebetween about 2 and about 25% by weight of the total solids in thecoating composition and preferably comprises about 5-40% by weight ofthe basecoat composition.

Pigments may be incorporated into the basecoat composition to providethe desired cosmetic characteristics. This is done by mixing pigmentswith the above-described grind resin, and in addition, optionally,aminoplast resin to form a pigment paste. In a preferred embodiment, themethodology of preparing a pigment paste with the nonionic polyurethaneresins of the present invention has been simplified in comparison tothat used to make pigment paste with anionic polyurethane resins. Inthis method, the nonionic polyurethane resin is simply mixed withpigment. Aminoplast cross-linking agents may also be added, but suchaddition is not preferred.

The final pigment paste comprises about 3% to about 65% by weight of apigment, and about 5% to about 65% by weight of a laterally orterminally stabilized polyurethane resin and optionally, up to 50% byweight of a cross-linking agent.

Any standard pigment known in the art may be used with resins of thepresent invention so long as these pigments can be formulated withoutaffecting the desired characteristics of the resins. Specific examplesof the dye stuffs or pigments may be inorganic or organic, for example,graphite, carbon black, zinc chromate, strontium chromate, bariumchromate, lead chromate, lead cyamide, titanium dioxide, zinc oxide,cadmium sulfide, iron oxide, aluminum flakes, zinc sulfide, phthalocyanine complexes, naphthol red, quinacridones and halogenatedthioindigo pigments, among others.

Preferred aluminum flake pigments are available from Silberline Corp,Lansford, Pennsylvania or from Eckart Werke, Gunterstahl, West Germany.The aluminum flake pigments provide the coating with an enhanced"metallic veneer". In a preferred embodiment of the present inventionstandard grade aluminum stabilized with phosphate ester is used. Othermetallic flake pigments, for example, silver may also be used. Themetallic pigments may also be mixed with non-metallic pigments, butthese are to be carefully chosen so as not to diminish the desiredmetallic effect.

The resinous dispersions of the basecoat in compositions are dispersedin deionized water. It is preferred that the deionized water haveconductance readings of less than 13 micromhos⁻¹ and most preferablyless than about 5 micromhos⁻¹ to prevent gassing caused by the reactionof aluminum with water. Deionized water is also chosen to avoid saltsthat naturally occur in tap water. Other solvents may also be employedwith the deionized water. An especially preferred solvent is ButylCellosolve™ which aids mixing, formulating and dispersing pigment in thebasecoat composition. Other solvents can also be used, for example,low-boiling mono and polyhydric alcohols, ethers, esters, ketones andother organics. The organic solvent, which comprises at most about 80%of the basecoat composition, and preferably comprises about 10% to 20%by weight of the basecoat composition (including water) may be selectedto promote the dispersibility of individual components in the finalbasecoat composition (plasticizer characteristics) and for its lowvolatility characteristics.

A rheology control agent is also preferably incorporated into thebasecoat composition. The rheology control agent controls the viscosityof the resulting composition and is incorporated in amounts that willprevent sagging or running after a basecoat is sprayed onto a verticalsurface such as an automobile body. The direct result of incorporating arheology control agent is to provide flow control, body andsprayability. Another favorable result of adding a rheology controlagent is to allow for the deposition of a thicker coating, allowing morecomplete coverage of a substrate. The sprayed coatings containing theseagents also exhibit greater orientation of the flake pigments on thefinal coated substrate. Rheology control agents which can be used inembodiments of the present invention include the fumed silica compoundsand the bentonite clays. Preferred fumed silica compounds are thehydrophobic silica compounds, for example Aerosil R972, available fromDeGussa Corporation, (Frankfurt, West Germany). Another rheology controlagent which may be used, and in certain basecoat compositions, may bepreferred is a synthetic sodium lithium magnesium silicate hectoriteclay. An example of one such clay is Laponite RD, available fromLaporte, Inc (Saddlebrook, Jersey). In certain preferred embodimentsrheology control agents are mixed. The rheology control agent when it isincluded, generally comprises from 0% to about 20 percent by weight ofthe basecoat composition and preferably comprises between about 1percent and about 5 percent by weight of the final basecoat composition.

In general, the particle size of the rheology control agent plays a rolein the overall thixotropic properties of these resins. Rheology controlagents in embodiments of this invention are suspended in the material.It may be proposed that the suspended rheology control agents function,at least in part, through coulombic or electrostatic interactions.

In general, the particle sizes can be from less than 0.01 microns toover about 200 microns. These sizes can be adapted to develop in partthe rheology properties sought. In appropriate circumstances, theparticle sizes may be from about 1 to about 10 microns.

Any additional agent used, for example, surfactants, fillers,stabilizers, wetting agents, dispersing agents, adhesion promoters, etc.may be incorporated into the basecoat composition. While the agents arewell-known in the prior art, the amount used must be carefullycontrolled to avoid adversely affecting the coating and quick-dryingcharacteristics.

The final basecoat composition is adjusted to a pH of between 6.0 and8.0. Viscosity may be adjusted using deionized water. Final basecoatcompositions are comprised of the following components in the indicatedweight ratios.

                  TABLE I                                                         ______________________________________                                        General Description of a Silver Metallic Paint                                                    Amount (% by weight of                                                        Solids of Final Basecoat                                  Ingredient          composition)                                              ______________________________________                                        Polyurethane resin  20-80%                                                    Melamine             5-50%                                                    Rheology Control Agent                                                                             0-20%                                                    Pigment (Includes Aluminum Flakes)                                                                 0-20%                                                    Acid Catalyst        0-5%                                                     ______________________________________                                    

The basecoat compositions described hereinabove can be applied to ametal or plastic substrate in one or two coats using for example an airatomizer (Binks Model 60 spray gun, available from Binks ManufacturingCorporation, (Franklin Park, Ill.), or by using other conventionalspraying means. The basecoat compositions are preferably sprayed at a50-80psi, and a relative humidity of between 50 and 90% (optimally at60-80% relative humidity) and a temperature of 70°-90° F.

After being deposited, the basecoat compositions are flash dried withina temperature range of about room temperatures to about 145 degrees F.The preferred flash temperature is about 120 degrees. The flashconditions described herein result in about 90% of the solvents (waterplus organics) being flashed from the basecoat in this short period oftime.

After the first basecoat is deposited, a second basecoat can bedeposited over the first without drying (flash off), or alternatively, aclearcoat may be deposited over the flashed basecoat. It is a surprisingresult of the use of the nonionic resins of the present invention thatwhen straight shade (non-metallic) or metallic pigments are used, onecoat of basecoat might be used to provide excellent cosmeticcharacteristics. Any number of clearcoat compositions known in the artmay be used. Any known unpigmented or other transparently pigmentedcoating agent is in principle, suitable for use as a topcoat. A typicaltop coat composition contains 30-60% film forming resin and 40-70%volatile organic solvent

After the clear coat is coated onto the basecoat layer, the multi-layercoating is then baked to cross-link the polymeric vehicle and to drivethe small amount of residual water and organic solvent from themulti-layered polymeric composition. A preferred baking step involvesheating the coated substrate for a period of 10-60 minutes at atemperature of between 150 and 300 degrees F. The baking step cures thecoating to a hard, durable film.

The final multi-layer coated substrate comprises:

(a) a waterborne basecoat composition comprising about 20 to about 80%by weight of said basecoat composition of a polyurethane composition;

(b) about 5% to about 50% by weight of a cross-linking agent;

(c) optionally, up to about 20% by weight of a rheology control agent;

(d) about 5% to about 65% by weight of a pigment paste; and

(e) a clear top coat.

The invention will be further described in connection with severalexamples which follow. These examples are shown by way of illustrationof the invention and are not meant to limit the scope of the invention.All parts and percentages in the examples are by weight unless otherwiseindicated.

EXAMPLE 1 Preparation of Polyester Resin A

A polyester polyol resin is prepared by charging a reaction vessel flaskequipped with a fractionating column, with 551.9 g (15.8% of thepolyester resin) of isophthalic acid, 1923 g (54.9%) Empol 1010 (dimerfatty acid available from Emery Chemical Co.), and 1025.1 g (29.3%) of1,6-hexanediol and 100 g of toluene. Additional toluene may be added tofill the trap. The mixture was heated under nitrogen and the water ofcondensation was removed. During this heating 35.7 g of water isdistilled off. Heating was continued at approximately 200 degrees C.until the acid number is less than or equal to 8. The remaining tolueneis then vacuum stripped at 200° C. to produce a polyester resin for usein the polyurethane resin.

EXAMPLE 2 Preparation of Polyester B

A reaction vessel is charged with 960.0 g (43.5 WGT %) of neopentylglycol, 664.6 g (30.1 WGT %) of isophthalic acid, 584.7 g (26.5 WGT %)of adipic acid, and 50.0 g of toluene. The mixture is heated undernitrogen to 240° C. until an acid number of 3.5 is reached.

EXAMPLE 3 Preparation of Terminally Stabilized polyurethane resin

42.0 g of methoxy polyethylene oxide of 2000 equivalent weight, 88.5 gof IPDI, and 50.0 g of glycol ether PM acetate are charged to a reactorand heated to 95° C. for 2 hours under nitrogen. The mixture is cooledto 30° C., then 252.0 g of polyester A, 9.7 g of neopentyl glycol, and25.0 g of trimethylolpropane are added. The mixture is heated to 110° C.until all NCO groups have reacted. The mixture is cooled to 80° C. then90.0 g of isopropanol is added. The mixture is further cooled to 68° C.and 420.0 g of deionized water is added in under vigorous agitation over10 minutes. The resulting dispersion has a solids content of 42.4% andan average particle size of 140 nm.

EXAMPLE 4 Preparation of Terminally Stabilized Polyurethane resin

44.1 g of a butanol-initiated random copolymer of 75% ethylene oxide and25% propylene oxide of 2100 equivalent weight, 88.5 g of IPDI, and 50.0g of glycol ether PM acetate are charged to a reactor and heated to 95°C. for 2 hours under nitrogen. The mixture is allowed to cool to 30° C.and 260.6 g of polyester A, 9.7 g of neopentyl glycol, and 25.0 g of TMPare added. The mixture is heated to 100° C. until all NCO groups havereacted. The mixture is cooled to 82° C. and 90.0 g of isopropanol isadded in. The mixture is further cooled to 57° C. and 420.0 g ofdeionized water is added in under vigorous agitation over 1 hour. Theresulting dispersion has a solids content of 43.0% and an averageparticle size of 190 nm.

EXAMPLE 5a Preparation of Laterally Stabilized Polyurethane ResinPreparation of a methoxypolyether diol

A carbowax diol is prepared by charging a flask with 4538 grams ofmethoxypolyethylene glycol 2000 and 1015 grams of toluene. The mixtureis heated to reflux to remove the water present in the carbowax. Whenall the water has been removed the temperature of the batch is loweredto 50° C. and 4.5 grams of benzoyl chloride is added and allowed to mixfor 10 minutes. At this point 394.7 g of toluene diisocyanate is addedto the flask and heated to 70° C. and held until the appropriateisocyanate value is reached. The heat is turned off and 249 grams ofdiethanolamine is added to the flask. When the exotherm has ended thebatch is held 10 minutes. Then a vacuum strip is started to remove allthe toluene. Once all the toluene is removed, the diol is ready to beused in the polyurethane formation.

Preparation of a polyurethane resin

A flask is charged with 600 grams of polyester A (example=1), 100 gramsof carbowax diol, 50.2 grams of neopentyl glycol, 249.8 grams ofisophorone diisocyanate, and 205 grams of propylene glycol monomethylether acetate. The mixture is heated to 125° C. and reacted to aconstant isocyanate value. Then 44.8 grams of trimethyolpropane is addedand reacted for 1 hour at 125 degrees C. Then the batch is cooled to110° C. and 362.2 grams of ethylene glycol monobutyl ether is added.Then 1632.2 grams of deionized water is added under high agitation toform a dispersion.

EXAMPLE 5B Grind resin--laterally stabilized non-ionic p-polyesterpolyurethane Preparation of a carboxax diol

A carbowax diol is prepared by charging a flask with 4538 grams ofmethoxypolyethylene glycol 2000 and 1015 grams of toluene. The mixtureis heated to reflux to remove the water present in the carbowax. Whenall the water has been removed the temperature of the batch is loweredto 50° C. and 4.5 grams of benzoyl chloride is added and allowed to mixfor 10 minutes. At this point 394.7b grams of toluene diisocyanate isadded to the flask and it is heated to 70° C. and held there until theappropriate isocyanate value is reached. The heat is turned off and 249grams of diethanolamine is added to the flask. When the exotherm hasended the batch is held for 10 minutes. Then a vacuum strip is startedto remove all the toluene. Once all the toluene is removed, the diol isready to be used in polyurethane formation.

Preparation of a polyurethane resin

A flask is charged with 600 grams of polyester A (example=1), 100 gramsof carbowax diol, 50.2 grams of neopentyl glycol, 249.8 grams ofisophorone diisocyanate, and 205 grams of propylene glycol monomethylether acetate. The mixture is heated to 125° C. and reacted to aconstant isocyanate value. Then the batch is cooled to 110° C. and 35grams of diethanolamine is added. Then 1632.2 grams of deionized wateris added under high agitation to form a dispersion.

EXAMPLE 6 Preparation of a Terminally stabilized Polyurethane Resin

643.5 g of polyester A, 201.0g of methanol-initiated polyethylene oxideof 1350 equivalent weight, 145.0 g of 17 IPDI, and 175.0 g of methylpropyl ketone are charged to a reactor and heated to 124° C. undernitrogen until a constant NCO equivalent value is obtained. Next, 25.8 gof TMP is added and heating to 124° C. was resumed. After 2 hoursreaction time, all NCO groups have reacted, and 255.0 g of monobutylglycol ether is added. The mixture is cooled to 80° C. and 1775 g ofdeionized water is added in over 10 minutes under vigorous agitation.The resulting dispersion has a solids content of 31.3% and an averageparticle size of 60 nm.

EXAMPLE 7 Preparation of Terminally Stabilized polyurethane resin

455.0 g of polyester B, 155.0 g of methanol-initiated polyethylene oxideof 1450 equivalent weight, 10.0 g of TMP, 131.0 g of IPDI, and 132.0 gof methyl propyl ketone are charged to a reactor and heated to 105° C.under nitrogen for six hours, at which time no NCO groups remainunreacted. 200.0 g of monobutyl glycol ether is added and the mixture iscooled to 70° C. Next, 1370.0 g of deionized water is added in over 10minutes under vigorous agitation. The resulting dispersion has a solidscontent of 31.5% and a Gardner viscosity of E.

EXAMPLE 8 Preparation of silver metallic basecoat using laterallystabilized nonionic resin

    ______________________________________                                                                      WGT %                                           Component         Parts by Weight                                                                           Non-Volatiles                                   ______________________________________                                        2% Laponite paste 242.2       3.2                                             Resin from example 5                                                                            201.1       47.7                                            Aluminum paste (ALCOA 87575)                                                                    32.9        14.9                                            Phosphate ester solution                                                                        1.4         0.9                                             Melamine (Cymel 303)                                                                            51.1        31.8                                            p-Toluenesulfonic acid                                                                          9.1         1.5                                             catalyst (amine blocked)                                                      deionized water   162.2                                                       ______________________________________                                    

The polyurethane resin from example 5 is slowly added to the 2% Laponitepaste under vigorous agitation. In a separate container the aluminumslurry is prepared by mixing the aluminum paste, phosphate estersolution, and melamine under agitation. The aluminum slurry is slowlyadded to the resin mixture under high agitation. Deionized water isadded to reduce the viscosity of the paint to 14 seconds (#2 FISHERCUP). The pH of the paint is 6.7.

EXAMPLE 9 Preparation of silver metallic basecoat using terminalstabilization nonionic resin

The paint is prepared according to the process of example 8 except theterminally stabilized polyurethane resin of example 4 is used. The painthas a viscosity of 14 seconds (#2 FISHER CUP).

Comparison study Lateral stabilized vs. terminal stabilized silvermetallic basecoats

The silver metallic basecoats from examples 8 and 9 were sprayedside-by-side using a siphon automatic spray gun. Both paints weresprayed at 65 PSI over primed steel panels at 82° F. and 44% relativehumidity. The panels were baked at 250 degrees F for 30 minutes and themetallic effect was evaluated by comparison with a series of fivestandard silver metallic panels (1=best). Results were as follows:

    ______________________________________                                        Silver Paint Metallic Effect (1 = best)                                       ______________________________________                                        example 8    5.0                                                              example 9    3.0                                                              ______________________________________                                    

The silver metallic basecoats from examples 8 and 9 were resprayed at 68degrees F. and 80% relative humidity to test for the sag resistance ofthe paint. After baking the panels for 30 minutes at 250 degrees F., arelative sag resistance value was assigned to each panel (1=best; nosag, 5=worst; excessive sag). Results are as follows:

    ______________________________________                                        Silver Paint Sag Resistance (1 = best)                                        ______________________________________                                        example 8    5                                                                example 9    1                                                                ______________________________________                                    

The following examples of pigment grind pastes and straight-shade paintare applicable to both types of urethanes (i.e., lateral stabilizationand terminal stabilization).

EXAMPLE 10 Preparation of a TiO₂ pigment caste Dispersion of TiO₂

The nonionic urethane dispersions have been used to mill TiO₂ forexample, as supplied by DuPont, Glidden, etc., and more specifically,using DuPont R960HGHG as in the example below:

    ______________________________________                                                       Grams   Grams Non-Volatile                                     ______________________________________                                        Nonionic Urethane Dispersion                                                                   1452      450                                                DuPont R960HGHG  2250      2250                                               Deionized Water   331                                                         ______________________________________                                    

The urethane dispersion is placed in a two gallon vessel equipped with apropellor type agitator. The dry TiO₂ is added to the stirreddispersion. Deionized water is used to maintain a fluid paste. After thepigment is added, the slurry is stirred for 30 minutes. The viscosity isadjusted to 75-95 Krebs units (700-1500 cps) with water. Stirring iscontinued for 15 minutes. The paste is fed through a gravity fedsandmill as obtained from Chicago Boiler Company, charged with ceramicor glass media. Particle sizes of 0-6.5 microns is reached in one or twopasses.

EXAMPLE 11 Preparation of a Blue Pigment Paste Dispersion ofPhthalocyanine Blue Pigments

The nonionic urethane dispersions have been used to mill phthalocyaninepigments for example, those supplied by Ciba Geigy, Toyo Ink, SunChemical, etc., and more specifically Ciba Geigy X3485 as in the examplebelow:

    ______________________________________                                                       Grams Grams Non-Volatile                                       ______________________________________                                        Nonionic urethane dispersion                                                                   1781    552                                                  Ciba Geigy X3485  276    276                                                  ______________________________________                                    

The urethane dispersion is placed in a two gallon vessel equipped with apropellor type agitator. The dry pigment is added to the stirreddispersion. After the addition of the pigment, the slurry is stirred 30minutes. Deionized water may be added if necessary to achieve aviscosity of 60-85 Krebs units (500-1000 cps). Stirring is thencontinued for 15 minutes The paste is then fed through a gravity fedsandmill as described above until the particle size is 0-12 microns.

EXAMPLE 12 Preparation of a Perylene Pigment Paste Dispersion ofPerylene Pigments

The nonionic urethane dispersions have been used to mill perylenepigments as supplied by Mobay, BASF, etc., more specifically Mobay R6424in the example below:

    ______________________________________                                                       Grams Grams Non-Volatile                                       ______________________________________                                        Nonionic urethane dispersion                                                                   2419    774                                                  Mobay R6424       581    581                                                  Deionized Water   109                                                         ______________________________________                                    

The urethane dispersion is charged into a two gallon vessel equippedwith a propellor type agitator. The dry pigment is added to the stirreddispersion. Stirring is continued for 30 minutes after the pigment hasbeen added. Deionized water is used to obtain a viscosity of 50-85 Krebsunits (200-1000) cps). The slurry is then added to an attritor assupplied by Union Process, Akron, Ohio, charged with stainless steelshot. After 4-8 hours the particle size is 0-6.5 microns.

EXAMPLE 13 Preparation of a Carbon Black Pigment Paste Dispersion ofCarbon Black Pigments

The nonionic urethane dispersions have been used to mill carbon blackpigments from De Gussa, Columbian Chemicals, Cabot, etc., morespecifically Cabot Black Pearls 1300 in the example below:

    ______________________________________                                                       Grams   Grams Non-Volatile                                     ______________________________________                                        Nonionic Urethane Dispersion                                                                   2800      896                                                Cabot Black Pearls 1300                                                                         224      224                                                ______________________________________                                    

The urethane dispersion is charged into a two gallon vessel equippedwith a propellor type agitator. The dry pigment is added to thedispersion. Stirring is continued for 30 minutes after the pigment hasbeen added. If necessary deionized water is used to obtain a viscosityof 50-85 Krebs units (200-1000 cps). The slurry is then added to anattritor as supplied by Union Process, Akron, Ohio, charged withstainless steel shot. After 4-8 hours the particle size is 6-12 microns.

EXAMPLE 14 Preparation of a Nonionic White Basecoat

    ______________________________________                                                       # Pigment                                                                             # Vehicle 100#                                         ______________________________________                                        A.  Laponite         2                                                            Pluriol P900               2                                                  DI H.sub.2 O                                                                  Total for A                        13.9                                   B.  Melamine (Cymel 303)       31.4    6.53                                       Butyl Cellosolve                   1.62                                   C.  Nonionic urethane          33.5    21.7                                       Dispersion                                                                D.  Fumed Silica (R-972                                                                            9.5                                                          From DeGussa)                                                                 Melamine                   4.61                                               Nonionic disperson         8.74                                               Total                              16.2                                   E.  White grind paste                                                                              100.0     19.8    38.2                                       (Example 11)                                                              F.  Oxazolidine                2.29    1.91                                       blocked pTSA                                                              ______________________________________                                    

Part A is mixed under high agitation for 2 hours. Part B is added slowlyunder agitation followed by Part C. Part D is ground separately in amill and it and parts E and F are added under agitation. Finaladjustments in viscosity are made with deionized water. The pH of thebasecoat is 6.0-8.0.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be affected within the spirit and scope of theinvention and that the scope of the invention is to be determined by theclaims appended hereto.

What is claimed is:
 1. A basecoat composition for spraying or depositingonto a metal or plastic substrate comprising:(1) a laterally stabilizedpolyurethane resin comprising the reaction product of:(a) at least oneorganic compound having two or more reactive hydrogen functionalities;(b) a nonionic stabilizer prepared by the reaction of:(i) a polyetherhaving at least one active hydrogen group with a first polyisocyanatecompound to produce a partially capped isocyanate intermediate; and (ii)a compound having at least one active amine hydrogen and at least twoactive hydroxyl groups; and (c) at 1east one second polyisocyanatecompound; (2) a cross-linking agent; (3) a grind resin; and (4) apigment component.
 2. A basecoat composition according to claim 1wherein said at least one organic compound having two or more reactivehydrogen functionalities is selected from the group consisting orpolyester polyols, diols, triols and mixtures thereof.
 3. The basecoatcomposition according to claim 1 further comprising a rheology controlagent.
 4. The basecoat composition according to claim 1 wherein saidcross-linking agent is selected from the group consisting of aminoplastresins and capped polyisocyanates.
 5. The basecoat composition accordingto claim 1 wherein said polyether is prepared by a monoalcohol initiatedpolymerization of ethylene oxide, propylene oxide or mixtures thereof.6. The basecoat composition according to claim 2 wherein said polyetherhas a molecular weight of between 1200 and
 3000. 7. The basecoatcomposition according to claim 1 wherein said compound having at leastone active amine hydrogen and at least two active hydroxyl groups isdiethanolamine.
 8. The basecoat composition according to claim 2 whereinsaid cross-linking agent is selected from the group consisting ofaminoplast resins and polyisocyanates.
 9. The basecoat compositionaccording to claim 1 wherein said polyisocyanate of said nonionicstabilizer is selected from the group consisting of isophoronediisocyanate and 2,4 toluenediisocyanate.
 10. The basecoat compositionaccording to claim 1 wherein said second polyisocyanate compound isselected from the group consisting of isophorone diisocyanate and 2,4toluenediisocyanate.
 11. The basecoat composition according to claim 1wherein said polyurethane resin is further reacted with a capping agent.12. The basecoat composition according to claim 11 wherein said cappingagent is selected from the group consisting of trimethylolpropane,ethanolamine, and diethanolamine.
 13. The basecoat composition accordingto claim 1 wherein said organic compound is selected from the groupconsisting of a polyester polyol, an alcohol-containing compound or amixture thereof.
 14. The basecoat composition according to claim 13wherein said diol is a low molecular weight diol selected from the groupconsisting of ethylene glycol, propylene glycol, butylene glycol,neopentyl glycol, and 1,6-hexanediol.
 15. The basecoat compositionaccording to claim 13 wherein said triol is selected from the groupconsisting of trimethylolethane, trimethylolpropane, andpentaerythritol.
 16. The basecoat composition according to claim 13wherein said polyester polyol, diol, triol or a mixture thereofcomprises at moat about 20 percent by weight of said polyurethane resin.17. The basecoat composition according to claim 10 wherein said diols,triols, and mixtures, thereof comprise between about 1% and 6% by weightof said polyurethane resin.
 18. The basecoat composition according toclaim 1 wherein said second isocyanate-containing compound comprisesabout 10% to about 30% by weight of the final polyurethane resin.
 19. Abasecoat composition for spraying or depositing onto a metal or plasticsubstrate comprising:(1) a terminally stabilized polyurethane comprisingthe reaction product of:(a) at least one organic compound having atleast two active hydrogen groups; (b) at least one polyether having atleast one active hydrogen functionality, and (c) a polyisocyante; (2) across-linking agent; (3) a grind resin; and (4) a pigment component. 20.The basecoat composition according to claim 19 further comprising atleast one trifunctional hydroxyl-containing monomer.
 21. The basecoatcomposition according to claim 19 wherein said cross-linking agent isselected from the group consisting of aminoplast resins and cappedpolyisocyanates.
 22. The basecoat composition according to claim 19wherein said polyether is prepared by a monoalcohol initiatedpolymerization of ethylene oxide, propylene oxide, or mixtures thereof.23. The basecoat composition according to claim 20 wherein saidpolyether has a molecular weight of between 1200 and
 3000. 24. Thebasecoat composition according to claim 19 wherein said polyurethaneresin is further reacted with a capping agent.
 25. The basecoatcomposition according to claim 24 wherein said capping agent is selectedfrom the group consisting of trimethylolpropane, ethanolamine, anddiethanolamine.
 26. The basecoat composition according to claim 19wherein said organic compound is selected from the group consisting ofpolyester polyols, alcohol-containing compounds and mixtures thereof.27. The basecoat composition according to claim 26 wherein saidalcohol-containing compound is a diol, triol, or mixture thereof. 28.The basecoat composition according to claim 27 wherein said diol is alow molecular weight diol selected from the group consisting of ethyleneglycol, propylene glycol, butylene glycol, neopentyl glycol, and1,6-hexanediol.
 29. The basecoat composition according to claim 27wherein said triol is selected from the group consisting oftrimethylolethane, trimethylolpropane, and pentaerythritol.
 30. Thebasecoat composition according to claim 27 wherein saidalcohol-containing compound comprises at most about 20 percent by weightof said polyurethane resin.
 31. The basecoat composition according toclaim 30 wherein said alcohol-containing compound comprises betweenabout 1% and 6% by weight of said polyurethane resin.
 32. The basecoatcomposition according to claim 21 wherein said capped polyisocyanatecomprises about 10% to about 30% by weight of the final polyurethaneresin.
 33. The basecoat composition according to claim 19 wherein saidorganic compound is selected from the group consisting of polyesterpolyols, diols, triols and mixtures thereof.
 34. The basecoatcomposition according to claim 33 wherein said diol is selected from thegroup consisting of ethylene glycol, propylene glycol, butylene glycol,neopentyl glycol, and 1,6-hexanediol.
 35. The basecoat compositionaccording to claim 63 wherein said triol is selected from the groupconsisting of trimethylolethane, trimethylolpropane, andpentaerythritol.
 36. The basecoat composition according to claim 19wherein said polyisocyanate is selected from the group consisting oftoluenediisocyanate and isophorone diisocyanate.
 37. The basecoatcomposition according to claim 27 wherein said diols, triols andmixtures thereof comprise at most about 20 percent by weight of saidpolyurethane resin.
 38. The basecoat composition according to claim 37wherein said diols, triols, and mixtures thereof comprises between about1% and 6% by weight of said polyurethane resin.
 39. The resin accordingto claim 19 wherein said polyisocyanate comprises about 10% to about 30%by weight of the final polyurethane resin.
 40. A basecoat compositionaccording to claim 1 further comprising a grind resin which is alaterally stabilized polyester-polyurethane resin.
 41. A basecoatcomposition according to claim 1 further comprising a grind resin whichis a terminally stabilized polyurethane resin produced from:(a) at leastone organic compound having at least two reactive hydrogenfunctionalities; (b) a polyether containing at least one activehydrogen; and (c) a polyisocyanate.
 42. The basecoat compositionaccording to claim 19 wherein said grind resin comprises a terminallystabilized polyurethane resin produced from:(a) at least one organiccompound having at least two reactive hydrogen functionalities; (b) apolyether containing at least one active hydrogen; and (c) apolyisocyanate.